BioMedical Admissions Test (BMAT) Practice Test 2026 - Free BMAT Practice Questions and Study Guide

When a signal is transmitted across a synapse, the first and immediate action is the release of neurotransmitter molecules from the presynaptic neuron into the synaptic cleft. This release occurs when an action potential reaches the axon terminal of the neuron, triggering the opening of voltage-gated calcium channels. The influx of calcium ions causes synaptic vesicles filled with neurotransmitters to fuse with the presynaptic membrane and release their contents into the synaptic cleft.

This process is crucial for communication between neurons, as the neurotransmitters then bind to receptors on the postsynaptic neuron, leading to either excitatory or inhibitory responses, depending on the type of neurotransmitter and receptor involved. This step is foundational in neurotransmission and is essential for the proper functioning of neural circuits in the brain and nervous system.

The other options represent processes that happen after the neurotransmitters have been released and have acted on the postsynaptic neuron, rather than immediately after the transmission of the signal.